• 한국의학물리학회지:의학물리
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• 제33권4호
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• pp.114-120
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• 2022

Purpose: Particle beam therapy is advantageous over photon therapy. However, adequately delivering therapeutic doses to tumors near critical organs is difficult. Nanoparticle-aided radiation therapy can be used to alleviate this problem, wherein nanoparticles can passively accumulate at higher concentrations in the tumor tissue compared to the surrounding normal tissue. In this study, we investigate the dose enhancement effect due to gold nanoparticle (GNP) when Carbon-12, He-4, and proton beams are irradiated on GNP. Methods: First, monoenergetic Carbon-12 and He-4 ion beams of energy of 283.33 MeV/u and 150 MeV/u, respectively, and a proton beam of energy of 150 MeV were irradiated on a water phantom of dimensions 30 cm×30 cm×30 cm. Subsequently, the secondary-particle information generated near the Bragg peak was recorded in a phase-space (phsp) file. Second, the obtained phsp file was scaled down to a nanometer scale to irradiate GNP of diameter 50 nm located at the center of a 4 ㎛×4 ㎛×4 ㎛ water phantom. The dose enhancement ratio (DER) was calculated in intervals of 1 nm from the GNP surface. Results: The DER of GNP computed at 1 nm from the GNP surface was 4.70, 4.86, and 4.89 for Carbon-12, He-4, and proton beams, respectively; the DER decreased rapidly with increasing distance from the GNP surface. Conclusions: The results indicated that GNP can be used as radiosensitizers in particle beam therapy. Furthermore, the dose enhancement effect of the GNP absorbed by tumor cells can aid in delivering higher therapeutic doses.

• 영어영문학
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• 제56권4호
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• pp.667-690
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• 2010

This essay attempts to read Percy Bysshe Shelley s The Mask of Anarchy by attending to a political agenda that Shelley seeks to propose and embody in the poem. This poem was written as a response to an exceptional political event, the Peterloo Massacre, and thus it is evident that Shelley intended to engage in contemporary politics by writing this poem. As many critics have pointed out, however, the way in which this poem addresses social, plitical issues is ambivalent and even confusing, since it contains many elements that contradict each other, and sometimes its political visions are based on incoherent conceptions. For this reason, this poem has been considered to be a failure as an occasional poem which should provide the reader with a clear direction for political actions. Faced with this critical problem, this essay proposes that the ambivalence this poem reveals-e.g., the confrontation between moderate artistic fantasy and radical tenets-is not a retreat from political activism, as some critics suggested, but a result of its creation and embodiment of a public sphere which invites various social classes and their positions. The mode in which Shelley conceives this unified public sphere in the course of writing The Mask of Anarchy can be interpreted in terms of the following three features. First, this poem underscores the significance of thoughts in constituting a communal space between people, thus asking the reader to participate in this process of thinking on given issues. Second, this poem suggests that people should enlighten each other by engaging in communicative reciprocations. Lastly, the public sphere formulated by the previous two features should incorporate various socio-political agents beyond class boundaries (even oppressors themselves) into its own working field. After explaining how these three features are manifested in the poem, this essay argues that the unified public sphere thus formed in the poem is the very agenda that Shelley aims to propose for the contemporaneous politics and culture. As a conclusion, this essay highlights how Shelley s project of creating a unified public sphere finally failed in contemporary history through observing two contrasting receptions of Shelley s works.

• 사물인터넷융복합논문지
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• 제10권1호
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• pp.53-58
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• 2024

4차 산업혁명의 핵심 기술인 IoT, Big-data, AI, Cloud 기술들이 최근 다양한 분야에서 신성장 동력의 핵심 기반 기술로 활용되고 있다. 이에 농업 분야에도 예외 없이 이러한 핵심 기술들이 적용되어 시공간의 제약 없이 원격 및 생산의 자동화를 통해 농업 분야의 문제점인 노동력 부족 현상 해결, 생산비 절감, 환경 부담 절감 등에 기여하고 있다. 그러나 이러한 핵심 기술을 활용함에 따라 농업 분야에도 보안 사고 사례가 발생하고 있다. 이에 본 연구에서는 스마트 팜을 기초, 중간, 고도의 3단계로 구분하여 단계별 특성, 보안 위협 및 대응 방안을 제시하고자 한다. 특히 클라우드 플랫폼하에서 컨테이너 기반 다양한 서비스 및 연구가 증대됨에 따라 이에 대한 보안 위협을 중심으로 대응 방안을 제시하고자 한다.

• 한국해양공학회지
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• 제37권6호
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• pp.273-281
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• 2023

Recently, offshore structures for eco-friendly energy, such as wind and solar power, have been developed to address the problem of insufficient land space; in the case of energy generation, they are designed on a considerable scale. Therefore, the scalability of offshore structures is crucial. The Korea Research Institute of Ships & Ocean Engineering (KRISO) developed multi-linked floating offshore structures composed of floating bodies and connection beams for floating photovoltaic systems. Large-scale floating photovoltaic systems are mainly designed in a manner that expands through the connection between modules and demonstrates a difference in structural response with connection conditions. A fluid-structure coupled analysis was performed for the multi-linked floating offshore structures. First, the wave load acting on the multi-linked offshore floating structures was calculated through wave load analysis for various wave load conditions. The response amplitude operators (RAOs) for the motions and structural response of the unit structure were calculated by performing finite element analysis. The effects of connection conditions were analyzed through comparative studies of RAOs and the response's maximum magnitude and occurrence location. Hence, comparing the cases of a hinge connection affecting heave and pitch motions and a fixed connection, the maximum bending stress of the structure decreased by approximately 2.5 times, while the mooring tension increased by approximately 20%, confirmed to be the largest change in bending stress and mooring tension compared to fixed connection. Therefore, the change in structural response according to connection condition makes it possible to design a higher structural safety of the structural member through the hinge connection in the construction of a large-scale multi-linked floating offshore structure for large-scale photovoltaic systems in which some unit structures are connected. However, considering the tension of the mooring line increases, a safety evaluation of the mooring line must be performed.

• 한국음향학회지
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• 제27권4호
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• pp.207-214
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• 2008

입체음향을 구현하는 방법으로는 다수의 스피커를 사용하는 다채널 음향재생 시스템과 2개의 스피커나 스테레오 헤드폰을 이용하는 2채널 음향재생 바이노럴 시스템이 있다. 그 중에서 공간 및 비용 상의 문제로 인하여 2채널을 이용한 음향재생시스템이 주목을 받고 있다. 일반적으로 2채널로 입체음향을 재생하기 위해서는 소리가 음원으로부터 청자의 두 귀에 이르는 경로를 모델링한 머리전달함수 (HRTF : Head Related Transfer Function)를 이용하지만 혼돈원추 상에서 음상정위의 혼돈을 주게 되므로 입체감을 저하시킨다는 단점이 있다. 본 논문에서는 2채널 입체음향 시스템을 효과적으로 구현하기 위하여 머리전달함수를 개선하는 알고리즘을 제안한다. HRTF 그룹화 및 심리음향을 이용하여 각 방향에 해당하는 주파수 스펙트럼 특성을 부각시키는 방법을 적용하였으며 시뮬레이션을 통하여 제안한 알고리즘이 정확한 방향감을 생성할 수 있음을 확인하였다.

• 전기전자학회논문지
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• 제28권2호
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• pp.168-173
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• 2024

화자인식은 개개인마다 다른 음성 주파수를 분석하여 미리 저장된 음성과 비교해 본인 여부를 판단하는 하나의 기술을 의미한다. 딥러닝 기반의 화자인식은 여러 분야에 적용되고 있으며, 펫 로봇도 그 중 하나이다. 하지만 펫 로봇의 하드웨어 성능은 딥러닝 기술의 많은 메모리 공간과 연산에 있어 매우 제한적인 상황이다. 이는 펫 로봇이 사용자와 실시간 상호작용에 있어 해결해야 할 중요한 문제점이다. 딥러닝 모델의 경량화는 위와 같은 문제를 해결하기 위한 하나의 중요한 방법으로 자리하였으며, 최근 많은 연구가 진행되고 있다. 이 논문에서는 특정한 명령어 형태인 펫 로봇용 음성 데이터 세트를 구축하고 잔차(Residual)를 활용한 모델들의 결과를 비교해 펫 로봇용 화자인식의 경량화 연구의 결과를 서술하며, 결론에서는 제안한 방법에 대한 결과와 향후 연구방안에 대해 서술한다.

• 터널과지하공간
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• 제34권2호
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• pp.127-142
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• 2024

수치해석 기법의 강건성은 다양한 모델링 조건에서 계산 성능이 유지되는 것을 의미하며, 새로운 해석기법 또는 수치코드는 벤치마크 테스트를 통해 강건성이 평가될 필요가 있다. TOUGH-FLAC 모델링 기법은 국내외적으로 이산화탄소 지중저장, 사용후핵연료 지층처분, 지열 개발 등 다양한 분야에 적용되었으며, 실험 계측자료, 다른 수치코드들과의 결과 비교를 통해 모델링 유효성이 분석되었다. 본 연구에서는 해석해를 갖는 열-수리-역학적 복합거동 문제를 토대로 TOUGH-FLAC 기법의 벤치마크 테스트를 수행하였다. 적용된 해석해는 완전히 포화된 지반에 점열원 작용 시 주변매질의 온도, 간극수압, 역학적 거동과 관계되며, 해석해와 수치모사 결과를 비교하여 TOUGH-FLAC 기법의 강건성이 평가되었다. 또한, 열-수리-역학 해석의 연계항, 유체 상변화, 시간증분이 복합거동 계산에 미치는 영향을 조사하였다.

• 문화기술의 융합
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• 제10권4호
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• pp.757-761
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• 2024

현대전의 모자이크전을 수행하기 위한 다중임무 모듈형 함정의 획득 필요성이 증대되고 있고, 이 모듈형 함정에는 국내연구개발한 장비/체계 뿐만 아니라 해외 구매한 유무인복합체계를 함께 탑재해야 하는 상황이다. 다중임무 모듈형 시제함을 성공적으로 설계/건조하고 적기 전력화하기 위해서는 제한된 공간과 시간에서 유연하게 설치할 수있도록 신기술 적용을 필요로 한다. 하지만 기존의 용접(welding) 설치 방식은 안전상의 문제 때문에 설계/건조에 융통성을 제한하고 있음은 물론 결함 및 보완사항을 시정하는데 소요되는 비용과 시간이 과대하다는 문제점을 내재하고 있다. 따라서 본 연구는 이러한 측면에서 유연성을 제공할 수 있도록 선진해군에서 개발/적용된 차세대 설치 장치 현황과 한국 함정에 적용한 현장 실증 결과를 소개한다.

• Nuclear Engineering and Technology
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• 제56권7호
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• pp.2718-2731
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• 2024

To ensure the operational safety of nuclear power plants, we present a Quadruped Inspection Robot that can be used for many types of steam generators. Since the Inspection Robot relies on the Holding Modules to grip the tube-sheet, it can be regarded as a hybrid robot with variable configurations, switching between 4-RRR-RR, 3-RRR-RR, and two types of 2-RRR-RR, and the variable configurations bring a great challenge to dimensional synthesis. In this paper, the kinematic model of the Inspection Robot in multiple configurations is established, and the analytical solution is given. The workspace mapping is analyzed by the solution-space, and the workspace of multiple configurations is decomposed into the workspace of 2-RRR to reduce the analysis complexity, and the workspace calculation is simplified by using the envelope rings. The optimization problem of the manipulator is transformed into the calculation of the shortest contraction length of the swing leg. The switching performance of the Inspection Robot is evaluated by stride-length, turning-angle, and workspace overlap-ratio. The performance indexes are classified and transformed based on the proportions and variation trends of dimensional parameters to reduce the number of optimization objective functions, and Pareto optimal solutions are obtained using an intelligent optimization algorithm.

• Geomechanics and Engineering
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• 제38권3호
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• pp.215-229
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• 2024

Because of the various patterns of deep-water inrush and complicated mechanisms, accurately predicting mine water inflows is always a difficult problem for coal mine geologists. In study presented in this paper, the water inrush channels were divided into four basic water diversion structures: aquifer, rock fracture zone, fracture zone and goaf. The fluid flow characteristics in each water-conducting structure were investigated by laboratory tests, and multistructure and multisystem coupling flow analysis models of different water-conducting structures were established to describe the entire water inrush process. Based on the research of the water inrush flow paths, the analysis model of different water inrush space structures was established and applied to the prediction of mine water inrush inflow. The results prove that the conduction sequence of different water-conducting structures and the changing rule of permeability caused by stress changes before and after the peak have important influences on the characteristics of mine water-gushing. Influenced by the differences in geological structure and combined with rock mass RQD and fault conductivity characteristics and other mine exploration data, the prediction of mine water inflow can be realized accurately. Taking the water transmitting path in the multistructure as the research object of water inrush, breaking through the limitation of traditional stratigraphic structure division, the prediction of water inflow and the estimation of potentially flooded area was realized, and water bursting intensity was predicted. It is of great significance in making reasonable emergency plans.